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By P. R. G. Bak

The integration of interactive computer graphics technology with data analysis tools can assist in the evaluation of deposit models: the super- imposition of mine openings on complex geology can be quickly perceived using dynamic visualisation, colour-coding and transparency control while analysis functions assist in quantifying displayed information. To illustrate the functionality of such integration a research prototype system is presented which allows the interactive visualisation and evaluation of deposit models comprising both structural boundaries and the distribution of continuous properties.

Jan 1, 1992

By H. Para, A. Aguirre, G. Artadi

Mining is a very important economical activity in Peru which has been recently developed without considering environmental aspects. Here, we show an experience at the Milpo mine, situated 4,200 meters above sea level; a mining company that has the value of being one of few from the last decade that is engaged in consolidating a model of environmental protection. The model includes aspects of contamination prevention and control, with bioindicators such as pasture cultivation, vegetables, forests, and hydrobiological species breeding. Socially, through means of development programs in natural areas, forestation and support to rural agriculture, together with environmental education, it is being demonstrated that it is possible to ensure tangible results in environmental conservation and the well-being of the populations around the mine.

Jan 1, 1998

By Phillip J. Maddex

During the last 10 years there have been many new developments in transport and handling equipment. Important technical and economic developments that can be used to reduce costs are; new terminal and materials handling concepts large river tows - 40,000 tons and 9000 hp towboats slurry loading and unloading of ocean vessels long distance pipelining of solids development of the shuttle train (unit train) large ocean barges ? 25,000+ tons ? pushed & towed 150,000 ton self-unloading super tankers - 300,000+ tons container shipping Some of these developments have been discussed at SME meetings in papers describing the transportation of minerals from new mines. But, only a few papers described improved transportation from older operations. Since transportation is a major part of the delivered cost for minerals, the economic benefits to be gained by putting new transportation developments to work are very substantial. Frequently good transportation planning and management makes the difference between a marginal ore body and a very profitable one.

Jan 1, 1972

By P. A. K. Wilkinson

This paper is concerned with the development of an in situ recovery of boric acid from a deep-seated colemanite deposit in California. The deposit contains 147 million tons of borate ore containing 6.4% boron oxide (B203). It is the largest undeveloped colemanite deposit in the United States and because of its unique occurrence and grade, in situ extraction appears to be the most economic viable process. The paper covers the geological, mineralogical, hydrological, well-field development, and extraction considerations leading to the initial pilot plant and subsequent demonstration plant phases of the project. Market potential aspects and preliminary economics of the project are also covered.

Jan 1, 1987

By C. P. Shen, H. C. Tsai, Bennie Chu, Y. S. Hsieh

The Pinglin tunnels are situated within the fold-and-thrust belt structural region in Taiwan, due to continent-arc collision and plate tectonic setting. The pilot tunnel TBM (§=4.8m) became stuck ten times with the standstills to date. The westbound main tunnel TBM (§=11.74m) was buried in a collapsing calamity. The main tunnel TBM shall identify and overcome the adverse geology with high volume of ground water ingress itself. This paper presents our experience and methodology through the adverse geology with Pinglin large TBM.

Jan 1, 1999

By Johannes Jäger

"A composite shell lining typically consists of an outer permanent sprayed concrete shell, a water proofing layer and an inner sprayed or cast concrete shell. Composite shell linings become more and more popular and have been built recently on large scale infrastructure projects. Surprisingly there is very little published literature on the actual structural design of composite linings. As a consequence there is a lack of common understanding on how to design a composite lining structure. Composite action of the outer shell (primary lining) initially carrying short term ground loads and the “unloaded” inner shell (secondary lining) require nonlinear concrete modelling to be able to assess the bearing capacity of the composite lining structure adequately. The composite action of the waterproofing membrane and the inner and outer shells can be considered either by simplified closed form solutions or by numerical models. Strength and stiffness parameters of membrane and concrete govern interaction of inner and outer shell. This paper should contribute to understanding composite lining behaviour with focus on the bearing capacity at limit state by taking into account the actual loading history. Possible ways and concepts on how to deal with these topics are presented, however a broader discussion on limit states of the composite lining materials – also in the long term will be required to come to an agreement on composite lining design methodology. INTRODUCTION Composite Lining Technology Traditionally the construction of shotcrete lined tunnels incorporates primary and secondary linings, separated by a sheet or a sprayable waterproofing membrane. The primary lining shotcrete is considered to be structurally temporary and the secondary lining to be permanent, leading to designs which ignore the bearing capacity of the primary lining in permanent condition. There was general perception that the shotcrete lining installed immediately at the tunnel face, experiencing strains up to 1% and even cracking in the early age, combined with mesh reinforcement additional support measures like lattice girder, spiles and bolts cannot be considered as a permanent structure. But also former shotcrete mixes showed significant weakness with respect to durability suggesting a more temporary nature of primary lining shotcrete. On the other hand it was clear that primary lining shotcrete does not disappear, it may lose probably a certain percentage of its bearing capacity, but discounting any contribution from the primary lining at all was considered inherently conservative. There were different strategies to account for the risk of reduced durability and bearing capacity of the primary lining, either by selecting moderate ground loads for the secondary lining design, by assuming that some residual load will be carried by the primary lining. This approach is very much based on experience. Another more rational possibility is to assume that the primary lining degrades into a rocklike material, which is weaker than the primary lining shotcrete but still imparts some strength to the ground around the secondary lining, but does not need to comply with any concrete design codes any more."

Jan 1, 2016

By Alex Lowson, Dan Tempelis

The Riverside Badlands Tunnel segment of the Metropolitan Water District of Southern California’s Inland Feeder Project, was lined with a segmented concrete primary lining and a welded steel final lining with the annulus filled with Low-Density Cellular Concrete (really a grout). The paper describes a numerical modeling technique that was developed to determine safe grout placement procedures to avoid pipe flotation, and shows the relationship between flotation and the rheology of the liquid grout. Design details of the steel liners are often not well suited to grout placement, and recommendations are given on how to improve this.

Jan 1, 2003

By Bruce E. Nesbitt, Paul G. Lhotka

At Lupin mine gold is spatially and genetically linked to zones of hydrothermal alteration in iron-formation which are symmetrically developed adjacent to late Archean quartz veins. Immediately adjacent to the veins, coarse grained, typically gold- and sulfide-poor, calc-silicate rocks are often present. These rocks comprise hedenbergite + quartz ± grossular garnet ± epidote ± scheelite ± calcite. Sulfides (pyrrhotite, arsenopyrite and loellingite) and gold are concentrated in the next zone and occur with hornblende-rich rocks comprised of hornblende, quartz, hedenbergite and grunerite. Furthest from the veins are gold- and sulfide-poor, grunerite-rich iron formation comprising grunerite, quartz, hornblende and sometimes magnetite. Although the alteration assemblages have similarities with skarns, they develop in iron formation, and are at best indirectly related to intrusive igneous rocks. Geological and geochemical data clearly indicate the calc-silicate rocks are metasomatic in origin.

Jan 1, 1990

By R. W. Smith

Though generally rather non-selective in nature long chain collectors nevertheless function in different ways in accordance with their own particular physical characteristics. Altering various parts of their structures such as chain length, type of chain, etc. can therefore substantially alter the adsorptive behavior of the collectors in a set environment. The effect of such structural differences of the collectors on physical parameters such as solubility, critical micelle concentration, acid or base strength, tendency to be expelled from the aqueous phase is discussed, as is also the effect of these parameters on flotation behavior.

Jan 1, 1989

By R. K. Mehta, M. G. Bersch

Characterization of an ore or mill product is routinely performed by time consuming and tedious chemical analyses, sink-float separations, etc. Additionally, these types of tests do not provide data concerning the interrelations and interlocking of the mineral constituents. This paper discusses some of the applications and capabilities of the Minerals and Material Science Research Center at The University of Alabama. Back-scattered electron images of coal, oil shale, complex suldfide, and tantalium ores were acquired using a JEOL 8600 electron microprobe with a NORAN (formerly Tracor Northern] 8500 image analysis system. Methods of analysis and typical results are discussed.

Jan 1, 1992

By J. A. Marts, R. C. Gilmore, Jr. Bogin, S. A. Saki, J. F. Brune, J. W. Grubb

"Most, if not all longwall gobs contain explosive gas zones (EGZs), i.e., zones of explosive methane-air mixtures that can cause – and have caused – mine fires and explosions. If the coal is prone to spontaneous combustion, oxygen penetration into the gob must be avoided. This paper summarizes the significant research findings from five years of computational fluid dynamics (CFD) modeling research conducted at the Colorado School of Mines (CSM) under funding from the National Institute for Occupational Safety and Health (NIOSH). CSM Researchers have developed CFD modeling techniques to identify where and under what circumstances EGZs can form in longwall gobs and how EGZ formation and oxygen penetration depend on the ventilation method, face and bleeder ventilation parameters, injection of inert gases and the operation of gob ventilation boreholes. Recognizing these explosion and fire hazards is an important first step in improving the safety of longwall coal mines. CSM modeling research has shown that EGZ formation can be effectively controlled by adjusting ventilation parameters, choosing the proper ventilation pattern and injecting inert gases where necessary. INTRODUCTION In a project sponsored by the NIOSH Office of Mine Safety and Health Research, researchers at the Colorado School of Mines have examined gas compositions and flows in longwall gobs in order to assess explosion and fire hazards. Since gob areas are inaccessible, researchers developed a series of computational fluid dynamics (CFD) numerical modeling tools to characterize these hazards. A variety of CFD models were developed to cover progressively sealed as well as bleeder ventilated gobs for both coal and trona mines. The explosion and fire hazards posed by EGZs in longwall gobs can be summarized as follows.• If the EGZ lies closely behind the longwall face, flames and pressures from an explosion can penetrate the shield supports and reach the active face area, creating blast trauma, burn hazards and toxic, unbreathable atmospheres. • EGZs can be pushed around inside the gob by roof collapses and cave-ins. If they get pushed out into the face area, sudden methane inundations and explosion hazards in face areas can result. • Fresh air flowing into the gob can create an explosion hazard as the gas composition in the gob moves from fuel-rich inert to explosive, creating EGZs. • Ignition sources inside the gob can be frictional ignitions or spontaneous combustion. • Bleeder ventilated gobs are surrounded on all sides by an EGZ that forms along the fringe areas between the fresh-air ventilated bleeder entries and the methane-rich interior of the gob. It is suspected that diffusion flames can propagate rapidly along these EGZ fringes if an ignition occurs"

Jan 1, 2015

By Richard W. Kimball, Fred B. Estep, Dwayne E. Easterling

This paper discusses the overall challenges to construct a 15,125.7 m (49,625 LF),wastewater drainage tunnel in Cobb County, Georgia by a joint venture of Gilbert Southern Corp. and S.A. Healy Co. and a construction manager Parsons, with Jacobs Associates as a subcontractor. The goal of the project is to provide wastewater retention during peak usage and is connected to a treatment facility near the Chattahoochee River. The primary component of the project is the TBM-driven hard rock tunnel. Additional works include drill and blast areas; four intake interceptors, two construction shafts and a 33.5 m (110 ft), diameter pump station shaft.

Jan 1, 2003

By Isobel Clark

Geostatistical methods of estimating ore reserves and other spatial phenomena are becoming increasingly wide spread in their use. Properly applied, Geostatistical estimation falls into two stages -- the "modelling" of the spatial variability within the study area; and the use of this spatial model to provide an appropriate estimation technique. The first stage usually consists of construction and interpretation of semi-variogram graphs, and the second is the development of the corresponding Kriging method. Because of the apparent subjectivity inherent to the first stage of a geostatistical analysis, attempts have been made to provide methods of "testing' whether a particular semi-variogram model (say) adequately represents the study area. Increasingly, the choice of model is being justified by a process known as "Cross Validation'. With this approach, the analyst uses a partial data set to estimate values at actual sampled positions. "Real" and "estimated" values are then compared in such a way that the model can be accepted or rejected. This paper discusses the process of cross validation in some detail, using case studies as examples. Some problems with the technique are illustrated and discussed.

Jan 1, 1986

By James J. Guesk, Robert W. Reisinger, Timothy C. Richmond

A high-altitude (2,900 m [9,500 ft]) historic underground copper mine in Wyoming is discharging copper-laden water with a neutral pH into an otherwise pristine creek. The Wyoming Abandoned Mine Land program is reclaiming the site under a CERCLA deferral agreement. The clean-up goal is to reduce copper in the mine discharge so that the creek can eventually support a trout fishery. A pilot-scale passive treatment test utilizing sulfate-reducing bacteria has been conducted at the site beginning in summer 1997. Test results show significant reduction in copper concentrations in near-freezing mine water at flow rates ranging to 19 liters per minute (5 gpm)

Jan 1, 2000

By J. Hanna, J. Jung, I. J. Anazia

Electrothermal production of elemental phosphorous (P4) generates substantial amounts of highly toxic phossy water and sludges. Because of their high phosphorous contents and lack of reliable processing technology, large tonnages of these hazardous wastes have accumulated from current and past operations. To date, the sludges are stored in ponds or above ground in special containment vessels at various locations around the country. Two samples of electric furnace phosphorous sludge (obtained from the Tennessee Valley Authority (TVA) in Muscle Shoals, AL and FMC Corporation in Pocatello, ID) were investigated using physical separation techniques to recover the elemental phosphorous and to render the residual material nonhazardous. The techniques tested include sizing, froth flotation and dispersed air oxidation. Flotation and sizing produced concentrates containing 69% - 90%P4, with recovery in the range of 60% - 87%. Dispersed air oxidation of the fines and tailings products was effective in the removal of an additional 10% - 15% of the P4 in the sludge.

Jan 1, 1993

By W. K. Collins, C. L. Dahlin, D. C. Dahlin, W. K. O’Connor, G. E. Rush

Direct mineral carbonation was investigated as a process to convert gaseous CO2, into a geologically stable final form. The process utilizes a slurry of water, with bicarbonate and salt additions, mixed with a mineral reactant, such as olivine (Mg2SiO4) or serpentine [Mg3Si2O5(OH)4]. Carbon dioxide is dissolved into this slurry, resulting in dissolution of the mineral and precipitation of magnesium carbonate (MgCO3). Optimum results were achieved using heat-pretreated serpentine feed material and a high partial pressure of CO2 (Pc02). Specific conditions include 155°C, PC02 = 185 atm and 15% solids. Under these conditions, a 78% conversion of the silicate to the carbonate was achieved in 30 minutes. Process mineralogy was utilized to investigate the appropriate feed characteristics, identify the process products and interpret the mineral dissolution and carbonate precipitation reaction paths. Key words: Mineral carbonation, Carbon dioxide sequestration, Carbonates

Jan 1, 2003

By Dennis L. Boley, Francesco Gallavresi, Donald A. Bruce

The authors describe novel aspects of ground reinforcement and treatment as related to soft ground excavation for tunnels throughout the world. Insitu reinforcement for cut slopes (soil nailing), as underpinning (reticulated micropiles), and as direct tunnel support (infilaggi) is introduced. Ground treatment focuses on new aspects of permeation grouting (by the tube'a manchette system), and on jet grouting-a very powerful and positive new technique. Recent developments in equipment, materials, methods and instrumentation are reviewed, with special reference to major tunnelling projects in Italy and Singapore.

Jan 1, 1987

By Richard R. Klimpel

INTRODUCTION Froth flotation is the most widely used and economic means of concentrating metal sulfide ores such as those containing copper, lead, zinc, nickel, molybdenum, and pyrite. Also recoverable are other metal species that are often associated with sulfide ores such as cobalt, platinum, gold, silver, etc. Froth flotation is a physico-chemical process for separating finely ground minerals from their associated gangue material. The process involves chemical treatment of a finely divided (ground) ore in a water pulp to create conditions favorable for the attachment of certain of the mineral particles to air bubbles. The air bubbles then carry the selected minerals, called valuable, to the surface of the pulp to form a stabilized froth which is removed and recovered. The unattached gangue material remains submerged in the pulp and is either discarded or reprocessed. To obtain the adherence of the desired mineral particles to the air bubbles, at least two specific steps must occur: a hydrophobic (water hating) surface film must be formed on the particles to be floated along with a hydrophillic (water wetting) film on all other particles; and a controlled bubble surface tension interface must be maintained, allowing for high particlelbubble collision frequency and efficient attachment or sticking of the particle to the bubble once collision has taken place. In most flotation applications, the above two steps are controlled by chemical flotation reagents. The collector is a chemical reagent which produces the hydrophobic film on the valuable mineral particle and is the primary driving force that initiates the flotation process. The frother is a chemical reagent which influences the collision frequency and attachment efficiency of hydrophobic particles and air bubbles. Thousands of research papers and books have been published on the chemical theory behind sulfide mineral collectors, e.g., Fuerstenau (1962), Fuerstenau (1976), Fuerstenau, et. al. (1985), King (1982), Leja (1982) and Moudgil and Somasundaran (1987), This article will only address and summarize some of the more practical aspects of collector usage. The industrial scale practice of froth flotation in sulfide mineral concentration has changed little since the 1950's. For example, of the approximately 80,000 metric tons of sulfide mineral collectors used commercially (1980) in the free world, almost 98% were known and manufactured in some form 25 years ago. A very interesting and informative history of collector development has been given by Crozier (1984). In addition, the industrial scale practice of froth flotation applied to sulfide ores has proceeded since the 1920's with often little direct (predictive) scientific explanation due to the extreme complexity of the flotation process. Empirical testing has been a mainstay of industrial flotation reagent development and use. Even today there is often strong disagreement between researchers as to the mechanisms of chemical flotation practices that have been performed successfully at an industrial scale for many years. As a result of the above environment which makes reagent cost/performance analysis difficult for new reagents, there is a strong tendency for the flotation operation to use, and reagent companies to supply, as cheap as possible raw materials and manufactured products that are quite general in application. In the last 20 years or so, there has been increasing technical effort to tailor make reagents for specific applications, but to date such work has had little commercial impact. It is clearly the hope of this author and others that this situation will change in future years as technology improves and pressure for improved flotation performance intensifies. This article is a condensation of collector usage trends quantified as part of a comprehensive industrially oriented applications program on froth flotation organized by Klimpel and coworkers (1979-1987) and as reported in various countries that participated in the program from 1978-1983. No attempt will be made to provide specific.

Jan 1, 1986

By J. M. Mutmansky, A. Wang

This paper defines the elements of a basic economic model for decision making when considering a methane drainage system for an underground coal mine. A drainage system entails significant capital and operating expense; hence the decision to utilize drainage must be made carefully. The model outlines the basic structure of decision making and considers the costs and benefits when the methane is marketed and when the methane is vented to the atmosphere. The effects on mine safety and the dust levels in the mine are also considered, both in a general format and as economic variables. Sources of information for executing this decision making are provided for an actual mine decision.

Jan 1, 1999

By Dennis D. Fischer

The second underground coal gasification experiment conducted by ERDA's Laramie Energy Research Center at a site near Hanna, Wyoming, was completed on July 30, 1976. During the experiment production reached 0.32 Mm 3/d (12 Mft3/d) of 6.9 MJ/m3 gas (175 Btu/ft 3 ). Approximately 6100 tonne (6700 ton) of coal were gasified during the experiment. Energy return ratios of 4.5 to 5.3, cold gas - thermal efficiencies of 76 to 89 percent, and overall process efficiencies of 65 to 74 percent were achieved during the second Hanna experiment. This paper describes the experiment and the results obtained with emphasis given to the determination of the energy recovered relative to energy consumed in conducting the test. Data from this determination are compared with previously published data from the first test conducted at Hanna during 1973-1974.

Jan 1, 1977